Recently, thinner and higher resolution camera modules have been required to be installed on mobile phones or the like. According to such requirements of thinner and higher resolution camera modules, image sensors have come to include more miniaturized pixels. Since an amount of light to be entered into pixels of an image sensor decreases as a pixel area is smaller, a signal amount decreases and a signal-to-noise ratio (SNR) deteriorates. It is desired, therefore, to improve light utilization efficiency to realize an image sensor having high sensitivity.